scholarly journals Multi-temporal analysis of radiometric changes in satellite images of forest edges to infer selective-logging areas in the Amazon forest

2015 ◽  
Vol 45 (1) ◽  
pp. 35-44 ◽  
Author(s):  
Paulo Maurício Lima de Alencastro GRAÇA ◽  
Francisco Dario MALDONADO ◽  
João Roberto dos SANTOS ◽  
Edwin Willem Hermanus KEIZER
Keyword(s):  
Satellite Images ◽  
Near Infrared ◽  
Elevation Angle ◽  
Temporal Analysis ◽  
Selective Logging ◽  
Amazon Forest ◽  
Forest Edges ◽  
Solar Elevation ◽  
Multi Temporal ◽  
Solar Elevation Angle

Radiometric changes observed in multi-temporal optical satellite images have an important role in efforts to characterize selective-logging areas. The aim of this study was to analyze the multi-temporal behavior of spectral-mixture responses in satellite images in simulated selective-logging areas in the Amazon forest, considering red/near-infrared spectral relationships. Forest edges were used to infer the selective-logging infrastructure using differently oriented edges in the transition between forest and deforested areas in satellite images. TM/Landsat-5 images acquired at three dates with different solar-illumination geometries were used in this analysis. The method assumed that the radiometric responses between forest with selective-logging effects and forest edges in contact with recent clear-cuts are related. The spatial frequency attributes of red/near infrared bands for edge areas were analyzed. Analysis of dispersion diagrams showed two groups of pixels that represent selective-logging areas. The attributes for size and radiometric distance representing these two groups were related to solar-elevation angle. The results suggest that detection of timber exploitation areas is limited because of the complexity of the selective-logging radiometric response. Thus, the accuracy of detecting selective logging can be influenced by the solar-elevation angle at the time of image acquisition. We conclude that images with lower solar-elevation angles are less reliable for delineation of selecting logging.

scholarly journals Monitoring and Landscape Quantification of Uncontrolled Urbanisation in Oasis Regions: The Case of Adrar City in Algeria

2021 ◽  
Vol 5 (2) ◽  
pp. 209-219
Author(s):  
Assoule Dechaicha ◽  
Adel Daikh ◽  
Djamel Alkama
Keyword(s):  
Landscape Metrics ◽  
Satellite Images ◽  
Methodological Approach ◽  
Monitoring And Evaluation ◽  
Temporal Analysis ◽  
Multi Temporal ◽  
Spatio Temporal ◽  
Landsat Satellite ◽  
Landscape Transformations ◽  
The City

Nowadays, uncontrolled urbanisation is one of the major problems facing Algerian oasis regions. The monitoring and evaluation of its landscape transformations remain a key step for any oasis sustainability project. This study highlights the evolution of spatial growth in the city of Adrar in southern Algeria during the period 1986-2016 by establishing a Spatio-temporal mapping and landscape quantification. The methodological approach is based on a multi-temporal analysis of Landsat satellite images for 1986, 1996, 2006 and 2016, and the application of landscape metrics. The results show two opposite spatial trends: significant growth of built-up areas against an excessive loss of palm groves. The landscape metrics allowed the identification of a progressive fragmentation process characterising the palm groves. Thus, the findings of this study show the utility of satellite imagery and landscape metrics approach for monitoring urbanisation patterns and assessing their impacts on oasis ecosystems.

Extracting icebergs freeboard from the shadows in Landsat-8 panchromatic images

2020 ◽  
Author(s):  
Zhenfu Guan ◽  
Yan Liu
Keyword(s):  
Large Scale ◽  
Accuracy Assessment ◽  
Elevation Angle ◽  
Absolute Error ◽  
Landsat 8 ◽  
High Precision Measurement ◽  
Solar Elevation ◽  
The Mean ◽  
The Antarctic ◽  
Solar Elevation Angle

<p><strong>Abstract:</strong> The iceberg freeboard is an important geometric parameter for measuring the thickness of the iceberg and then estimating its volume. Based on the fact that the iceberg can cast elongated shadow on the surface of sea ice in winter, this paper proposes a method to measure the iceberg freeboard using shadow length and the predefined or estimated solar elevation angle. Three Landsat-8 panchromatic images are selected to test our method, with center solar elevation angle of respectively 5.43°, 7.49°and 11.01° on August 29, September 7, and 16 September in 2016. Shadow lengths of five isolated tabular icebergs are automatically extracted to calculate the freeboard height. For the accuracy assessment, we use the matching points at the different time as cross validation. The results show that the measurement error of shadow length is less than one pixel. When the sun elevation angle is lower than 11.01°, the Root Mean Square Error (RMSE) of the iceberg freeboard from the panchromatic 15 m image is less than 2.0 m, and the Mean Absolute Error (MAE) is less than 1.5 m. Such experiment shows that: under the angle of low solar elevation in winter, the landsat-8 panchromatic 15 m image can be used for high-precision measurement of the iceberg freeboard, and has the potential to measure the Antarctic iceberg freeboard in large scale.</p><p><strong>Key </strong><strong>words:</strong> Antarctic, icebergs, freeboard, shadow altimetry, Landsat-8</p><p> </p>

Solar elevation angle probability distribution

Solar Energy ◽  
1980 ◽  
Vol 24 (4) ◽  
pp. 417-420 ◽  
Author(s):  
D.C. Larson ◽  
C.R. Acquista
Keyword(s):  
Probability Distribution ◽  
Elevation Angle ◽  
Solar Elevation ◽  
Solar Elevation Angle

scholarly journals MULTI-TEMPORAL ANALYSIS OF THE GLACIER RETREAT USING LANDSAT SATELLITE IMAGES IN THE NEVADO OF THE AMPAY NATIONAL SANCTUARY- PERU

2021 ◽  
Vol N/A (N/A) ◽  
pp. 0-0
Author(s):  
Carolina Soto Carrión ◽  
Juan José Zuñiga Negrón ◽  
Jhon Paucar Ancco ◽  
Wilber Jiménez Mendoza ◽  
Manuel J. Ibarra Cabrera ◽  
...  
Keyword(s):  
Satellite Images ◽  
Temporal Analysis ◽  
Glacier Retreat ◽  
Multi Temporal ◽  
Landsat Satellite

scholarly journals Latitude and Weather Influences on Sun Light Quality and the Relationship to Tree Growth

Forests ◽  
2019 ◽  
Vol 10 (8) ◽  
pp. 610 ◽  
Author(s):  
Camilo Chiang ◽  
Jorunn E. Olsen ◽  
David Basler ◽  
Daniel Bånkestad ◽  
Günter Hoch
Keyword(s):  
Light Quality ◽  
Elevation Angle ◽  
Spectral Composition ◽  
Weather Conditions ◽  
Seasonal Adjustment ◽  
Light Climate ◽  
Solar Elevation ◽  
Light Quantity ◽  
R:Fr Ratio ◽  
Solar Elevation Angle

Natural changes in photoperiod, light quantity, and quality play a key role in plant signaling, enabling daily and seasonal adjustment of growth and development. Growing concern about the global climate crisis together with scattered reports about the interactive effects of temperature and light parameters on plants necessitates more detailed information about these effects. Furthermore, the actual light emitting diode (LED) lighting technology allows mimicking of light climate scenarios more similar to natural conditions, but to fully exploit this in plant cultivation, easy-to-apply knowledge about the natural variation in light quantity and spectral distribution is required. Here, we aimed to provide detailed information about short and long-term variation in the natural light climate, by recording the light quantity and quality at an open site in Switzerland every minute for a whole year, and to analyze its relationship to a set of previous tree seedling growth experiments. Changes in the spectral composition as a function of solar elevation angle and weather conditions were analyzed. At a solar elevation angle lower than 20°, the weather conditions have a significant effect on the proportions of blue (B) and red (R) light, whereas the proportion of green (G) light is almost constant. At a low solar elevation, the red to far red (R:FR) ratio fluctuates between 0.8 in cloudy conditions and 1.3 on sunny days. As the duration of periods with low solar angles increases with increasing latitude, an analysis of previous experiments on tree seedlings shows that the effect of the R:FR ratio correlates with the responses of plants from different latitudes to light quality. We suggest an evolutionary adaptation where growth in seedlings of selected tree species from high latitudes is more dependent on detection of light quantity of specific light qualities than in such seedlings originating from lower latitudes.

scholarly journals Inclusion of Solar Elevation Angle in Land Surface Albedo Parameterization Over Bare Soil Surface

2017 ◽  
Vol 9 (8) ◽  
pp. 3069-3081 ◽  
Author(s):  
Zhiyuan Zheng ◽  
Zhigang Wei ◽  
Zhiping Wen ◽  
Wenjie Dong ◽  
Zhenchao Li ◽  
...  
Keyword(s):  
Land Surface ◽  
Surface Albedo ◽  
Elevation Angle ◽  
Soil Surface ◽  
Bare Soil ◽  
Solar Elevation ◽  
Solar Elevation Angle

scholarly journals UAV-Based Automatic Detection and Monitoring of Chestnut Trees

2019 ◽  
Vol 11 (7) ◽  
pp. 855 ◽  
Author(s):  
Pedro Marques ◽  
Luís Pádua ◽  
Telmo Adão ◽  
Jonáš Hruška ◽  
Emanuel Peres ◽  
...  
Keyword(s):  
Near Infrared ◽  
Vegetation Indices ◽  
Tree Height ◽  
Temporal Analysis ◽  
Individual Tree ◽  
Tree Detection ◽  
Sensing Platform ◽  
Agricultural Applications ◽  
Multi Temporal ◽  
Combination Bands

Unmanned aerial vehicles have become a popular remote sensing platform for agricultural applications, with an emphasis on crop monitoring. Although there are several methods to detect vegetation through aerial imagery, these remain dependent of manual extraction of vegetation parameters. This article presents an automatic method that allows for individual tree detection and multi-temporal analysis, which is crucial in the detection of missing and new trees and monitoring their health conditions over time. The proposed method is based on the computation of vegetation indices (VIs), while using visible (RGB) and near-infrared (NIR) domain combination bands combined with the canopy height model. An overall segmentation accuracy above 95% was reached, even when RGB-based VIs were used. The proposed method is divided in three major steps: (1) segmentation and first clustering; (2) cluster isolation; and (3) feature extraction. This approach was applied to several chestnut plantations and some parameters—such as the number of trees present in a plantation (accuracy above 97%), the canopy coverage (93% to 99% accuracy), the tree height (RMSE of 0.33 m and R2 = 0.86), and the crown diameter (RMSE of 0.44 m and R2 = 0.96)—were automatically extracted. Therefore, by enabling the substitution of time-consuming and costly field campaigns, the proposed method represents a good contribution in managing chestnut plantations in a quicker and more sustainable way.

scholarly journals Radiation balance diversity on NW Spitsbergen in 2010–2014

2017 ◽  
Vol 38 (1) ◽  
pp. 61-82 ◽  
Author(s):  
Marek Kejna ◽  
Marion Maturilli ◽  
Andrzej Araźny ◽  
Ireneusz Sobota
Keyword(s):  
Elevation Angle ◽  
Radiation Balance ◽  
The Sun ◽  
Net Income ◽  
Annual Variations ◽  
Solar Elevation ◽  
Diurnal Course ◽  
Polar Day ◽  
Solar Elevation Angle ◽  
North Western

AbstractThis article presents the results of observations of selected fluxes of the radiation balance in north-western Spitsbergen in the years from 2010 to 2014. Measurements were taken in Ny-Ålesund and in the area of Kaffiøyra, on different surface types occurring in the Polar zone: moraine, tundra, snow and ice. Substantial differences in the radiation balance among the various types of surface were observed. The observations carried out in the summer seasons of 2010–2014 in the area of Kaffiøyra demonstrated that the considerable reflection of solar radiation on the Waldemar Glacier (albedo 55%) resulted in a smaller solar energy net income. During the polar day, a diurnal course of the components of the radiation balance was apparently related to the solar elevation angle. When the sun was low over the horizon, the radiation balance became negative, especially on the glacier. Diurnal, annual and multi-annual variations in the radiation balance have a significant influence on the functioning of the environment in polar conditions.

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